The present invention relates to an apparatus and method for use in conducting leaching experiments on solids, including samples taken from stockpiles of ore, and/or tailings, or other mineral residues which are deposited on the surface of the land and exposed to the environment over extended periods of time. The leaching apparatus of the present invention is used to separate solid-phase materials and substances from rinse water containing soluble constituents dissolved from rock or ore bodies by percolation of water therethrough. The rinse water may then be analyzed to quantitatively determine the extent and nature of any contamination occasioned by contact of water and rock. Additionally, the solids may be maintained in a reasonably controlled environment, and weighed periodically to determine the extent of weight reduction occasioned by periodic exposure to water.
More particularly, the present invention relates to a method and apparatus which includes an upper leaching or holding chamber superimposed upon a plurality of serially arranged filter members. Vacuum means are provided to assist in the rapid transfer of the aqueous portions through some or all of said filter members. Use of such vacuum means, however, is not necessary if the particles that are to be filtered are relatively large. Pollutants and contaminants can enter water supplies either through ground water and/or surface water, and hence it is of interest to ascertain the extent to which solids, including dissolved solids are leached from the mineral residue samples.
It is well known in the prior art that solid phase materials can be separated from a liquid sample by transferring the liquid sample through a filter typically situated in a communicating passage between a first and a second container. Further, the prior art discloses the use of a vacuum assisted transfer between two receptacles having a filter interposed therebetween. See U.S. Pat. No. 3,782,175 issued to Michael H. Roman on Jan. 1, 1974, for example.
However, there is a real need in the art for an apparatus which incorporates a plurality of serially arranged and spaced apart filter elements wherein passage of liquid is assisted across all or certain selected filter elements by a vacuum. This is particularly true when it is desirable to test the environmental effects of earth surface wastes on rain water as it percolates through the wastes and subsequently flows to a subterranean aquifer or well or over the ground to form a supply source to a lake, stream, river or the sea. Such a device would most effectively permit one to quantitatively determine, experimentally, levels of dissolved solids comprising a source of potential contaminants such as sulfur, copper, nickel, cobalt, zinc, calcium, magnesium, sodium and potassium in an effluent. The apparatus also permits the conductance and pH of the resulting effluent to be determined experimentally. Further, the apparatus permits the solids to be weighed periodically to determine moisture content.
The principal object of the present invention is to provide a novel, inexpensive apparatus and method for removing constituent parts of solid mineral residues through leaching, gathering the effluent through filtration, and thereby determine the extent of leaching expected to occur in surface stored mineral residues, such as ore supplies, mineral tailings, and the like. Another object of the invention is to provide such an apparatus which economizes from the standpoints of space, solid sample requirement, and time.
Another object of the invention is to provide an apparatus for expeditiously separating an effluent from a mixture of solid mineral residue, particularly ore, tailings or other mineral solids, so that the degree of transfer of soluble components to the effluent can be determined.
Still another object of the invention is to provide an apparatus for determining experimentally the level of contamination to be expected in naturally occurring effluents, such as rainwater passing through a bed of mineral such as a stockpile of ore and/or tailings, said apparatus incorporating a plurality of filters, transfer of liquid through some of which is vacuum assisted.
A further object of the invention is to provide a method for separating an effluent from particulate solids so that the degree of potential contamination of the effluent can be determined, said method involving the use of an apparaus which includes an upper chamber, a lower chamber, a passageway between said upper and lower chamber in which a plurality of filter members are interposed, and means for providing a vacuum to assist transfer of the liquid across selected ones of said filter members.